This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-244236, filed Aug. 10, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
This invention relates to an oscillation suppression device for suppressing the oscillation of an object, such as a ship or gondola, whose oscillation is to be suppressed, using gyro torque.
2. Description of the Related Art
An oscillation suppression device using gyro torque is often installed in a ship. As described in, for example, Japanese Patent No. 2813540, a conventional oscillation suppression device comprises a base body secured to a ship body, a gimbals rotatably provided in the base body, a flywheel provided in the gimbals and a motor for spinning the flywheel at a high speed, etc. This motor, which is mounted in the gimbals, is a component that is not integrated with the gimbals or flywheel. The output shaft of the motor is connected to the rotary shaft of the flywheel via a coupler.
In the conventional oscillation suppression device, at least a part of the motor outwardly protrudes from the locus of rotation of the gimbals. Accordingly, when the ship rolls or pitches and the gimbals rocks relative to the base body, the part of the motor rotates along a circle with a radius greater than that of the locus of the gimbals.
In the conventional device, it is necessary to secure, in a ship, a large space required for the gimbals and motor to rock, i.e., required for the attachment of the oscillation suppression device. Moreover, the sound made by the rotation of the motor or flywheel is transmitted to the outside, and is loud. In addition, while the gimbals is rotating, it is possible that the limbs of a crew member standing near the device may be pinched by it.
It is an object of the present invention to provide a gyro-type oscillation suppression device that can be made compact.
An oscillation suppression device according to an aspect of the invention comprises: a base body having an attachment portion to be secured to an object whose oscillation is to be suppressed; a gimbals supported by the base body such that the gimbals can rotate around a first axis; a damper which suppresses rotation of the gimbals relative to the base body; a flywheel provided in the gimbals such that the flywheel can rotate around a second axis perpendicular to the first axis; and a motor which rotates the flywheel, the motor including a rotor member attached to the flywheel, and a stator member attached to the gimbals and opposed to the rotor member with a predetermined gap therebetween, characterized in that: the rotor member and the stator member are located inside a locus-of-rotation along which an outer peripheral of the gimbals rotates around the first axis; and the base body is provided with a cover portion which covers an outer surface of the gimbals.
When an object whose oscillation is to be suppressed has oscillated, the base body and gimbals rotate relative to each other. The term xe2x80x9crotationxe2x80x9d recited in this specification includes an angular displacement (rocking) of 360 degrees or less between the base body and gimbals. The gyro torque of the flywheel is exerted to suppress the oscillation of the object, whereby the oscillation of the object is suppressed.
In the oscillation suppression device of the invention, the gyro torque, generated while the flywheel is rotating, suppresses the oscillation of an object whose oscillation is to be suppressed. In the oscillation suppression device of the invention, the motor does not outwardly protrude from the gimbals, and hence the range of oscillation of the gimbals can be made smaller than in the conventional case. The invention can make a compact oscillation suppression device. Further, since the gimbals is covered with a cover portion, the operator or peripheral thing can be protected from being touched by the rocking gimbals, motor or flywheel, etc., and the noise generated therefrom can be reduced.
In the invention, the base body may have a monocoque structure, and a portion of the base body may serve as the cover portion. The base body of the monocoque structure, which also serves as the cover portion, has a high rigidity. This is advantageous for enhancing the strength of the device if a plurality of oscillation suppression devices are used in a vertically stacked state.
In the invention, at least a part of the rotor member may be received in a recess formed in an end face of the flywheel. If the rotor member included in the motor is received in the recess formed in the end face of the flywheel, the gimbals assembly including the motor can be made more compact.
In the invention, the damper may be a dashpot type damper which includes a short cylindrical housing containing a hydraulic fluid, a partition member rotatably received in the housing, and an orifice formed between a first liquid chamber and a second liquid chamber, the partition member partitioning an interior of the housing into the first and second liquid chambers, the partition member rotating within the housing in accordance with rotation of the base body relative to the gimbals. The housing of the damper is exposed to the outside of the cover portion to enhance its heat dissipation.
If the oscillation suppression device of the invention employs the dashpot type flat oil damper, the width of the device can be reduced. Moreover, if the gimbals bearings are built into side walls of the base body, the width of the oscillation suppression device can be further reduced.
Naturally, any structural element of the invention, such as the base body, gimbals, damper, flywheel, motor or cover portion, etc. may be appropriately modified without departing from the scope of the invention.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.